Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Maximum load - floor joists

  1. Nov 17, 2007 #1
    Hi everyone,

    I am remodeling a recently bought home. One of the upstairs rooms is a game room and I plan on putting a pool table (1000 lbs) in it.

    The original floor joists were 2x6 16" OC - I glued and nailed another joist on to existing joist - so now it is 4x6 16" OC. If I would add another joist in between, that would make the joist system 2x6 8" OC. The joist span is 13'.

    I wonder which one would be better, that is, 4x6 16" OC vs. 2x6 8" OC.

    How can I find out since there are no calculators I can find online that will allow me to get the appropriate spans as a function of sistered 4x6 joists or at a spacing of 8" OC?

    The thing is the former owner added a second story, but did not reinforce the 2x6 ceiling (floor for the 2nd floor) joists. He simply laid 2x4's perpendicular to the "ceiling" joists 16" OC and used a single layer of tounge and grooved 3/4" floor boards. Upon inspection there are many places where the crossing 2x4 do not even tough the underlying joists.

    The rest of information: Southern Pine grade #2; dead and live load of 10 and 40, respectively; L/360 deflection.

    Maybe you could help me with an exact answer or tell me where should I look to calculate myself.

    Thanks in advance!
  2. jcsd
  3. Nov 17, 2007 #2


    User Avatar
    Science Advisor

    If you are remodeling a purchased home, one thing I would watch out for is that, even though you did not do the work, since you are redoing things, you are responsible to bring it up to current code for your area. If you have any permits, you'll have to clear those and I would imagine that structural is part of that.

    Honestly, I would see what code is in your area and do your best to get to that. Especially if it was done incorrectly the first time.

    You'd be best off to get to a 2x8 with 16" centers, or even 12". But it sounds like you don't want to tear everything up. The beam's stiffness is more influenced by the height than the width which is why it should be a 2x8 preferably.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Maximum load - floor joists
  1. Load proportionality (Replies: 1)

  2. Load cell (Replies: 3)